Orthogonal Frequency Division Multiplexed (OFDM) transmission schemes are widely used in digital communications, including wireless networking, television and audio broadcasting, and internet access. In an OFDM scheme, the overall system bandwidth is partitioned into a number of orthogonal subcarrier frequencies, commonly referred to as tones. A stream of informational bits is converted to a series of frequency-domain symbols, and these symbols are transmitted over the subcarrier frequencies. Each subcarrier is modulated with a modulation scheme, such as quadrature amplitude modulation (QAM) or some form of phase-shift keying (PSK). OFDM is used in the IEEE 802.11 wireless local area networking standards.
Many techniques have been proposed to transmit pilot signals along with OFDM signals to allow receivers to estimate channel characteristics. One option is to add a distributed pilot channel probe to OFDM data being transmitted. When an OFDM transmitter adds a distributed pilot channel probe on top of OFDM data, the receiver must remove the distributed pilot signal before demodulating the data. Existing techniques for removal of a distributed pilot signal often require complex, iterative time domain estimation algorithms to separate the distributed pilot channel probe from the OFDM data. Accordingly, there remains a need for a more efficient way to remove distributed pilot signals from OFDM signals at a receiver.